Agriculture

Managing pests prevents damage to ag

State statute requires all residents to control noxious weeds

Since 1990, Colorado law has required management of non-native plants that threaten or disrupt the state's natural and agricultural resources.

The Colorado Noxious Weed Act, revised in 2003, establishes priority lists - A, B and C -- for weed control and enables county and city governments to manage noxious weeds through their own programs.

In Logan County, weed control dates back much farther than the state law. The Logan County Pest Control District is made up of five weed control district established as early as 1967, that consolidated in 1972.

Dave Appelhans, Pest District supervisor, said that while the consolidation "left some holes in the map," the district serves virtually all of Logan County. Cities and towns do not pay into the district, which is funded by a tax levy of 1 mil on properties in the district. The district also receives some state funding.

Purple loosestrife (Lythrum salicaria) is a List A noxious weed that can be found in Logan County. List A species must be eradicated wherever they are found, according to Colorado law. (Noxious Weeds of Colorado/ / Colorado Weed Management Association)

The first, five-member advisory board for the district was tasked with controlling six weeds: Canada thistle, field bindweed, silver-leaf poverty weed, woolly leaf, poverty weed, and whitetop.

Today, the number of plants on the control list has grown, but many of the same weeds remain a problem. Among the known noxious weeds in Logan County are: field bindweed, Canada thistle, musk thistle, Russian knapweed, diffuse knapweed, spotted knapweed, skeletonleaf bursage or silverleaf povertyweed, woolly leaf bursage or woolly leaf povertyweed, whitetop or hoary cress, perennial pepperweed or tall whitetop, jointed goatgrass, leafy spurge, purple loosestrife or purple lythrum, and showy milkweed. Purple loosestrife is a List A plant, which means it is designated for elimination on all county, state, federal and private lands. List B plants, including Canada thistle, Russian knapweed, diffuse knapweed, spotted knapweed, perennial pepperweed, jointed goatgrass and leafy spurge, should be stopped from spreading. The plants on List C, such as field bindweed and puncturevine, are selected from recommended control methods.

The Colorado Department of Agriculture has also created a watch list that includes plants known to be invasive that can be found in areas near Colorado but have not been found in the state.

The Noxious Weed Act requires all Colorado residents to use "integrated control methods" on noxious weeds to prevent damage to neighboring landowners.

According to Appelhans, many of the plants the state classifies as noxious weeds are ornamental plants that escaped into the wild, where they thrive and crowd out native plants. "You'll never see a native plant on the Colorado noxious weed list," he said.

Field bindweed (Convoluvulus arvensis), a member of the morning glory family, is so prolific that Pest District Supervisor Dave Appelhans jokes, "If you have it, you might as well name it." The common List C weed's extensive root formation creates colonies of the plant, and shallow tilling only increases the number of plants. (Noxious Weeds of Colorado / Colorado Weed Management Association)

Some of these ornamentals are still available as landscaping plants from nurseries, although Appelhans noted that if he sees List A species, even in town, he will notify the property owner that the plants must be removed and destroyed.

Other weeds have entered Colorado on agricultural equipment or vehicles traveling from other areas.

According to the "Noxious Weeds of Colorado" guide published by the Colorado Weed Management Association (CWMA), "Noxious weeds thrive becaue they have no natural controls, such as insects, and are able to adapt to varied climatic conditions." Some of the weeds were originally brought to the U.S. from overseas.

Spraying weeds on the county rights of way is only part of Appelhans' job. As the district supervisor, he is tasked with ensuring that everyone in the county complies with state law as far as noxious weed management is concerned.

The wet summer meant it was a bad year for weed growth, he said, but it was a good year as far as compliance went. Property owners with weed problems are notified by letter, and they were good about addressing the issues on their own or contacting him to work out a plan for control, he said. Typically, the district will only spray sites of 10 acres or less, or locations where access is difficult; otherwise, Appelhans said he refers private landowners to commercial pesticide applicators. That's part of his commitment to not compete with any local businesses.

Paperwork is also a big part of his job. The state requires detailed records of what is sprayed, when and where; fortunately, Appelhans said, the sprayers are equipped with technology that tracks their location using GPS and monitors ground speed and weather conditions to make that recordkeeping easier. He said he spends the cold months when he's not out in the field spraying catching up on the paperwork.

Another task for Appelhans is weed mapping. While it's not mandatory, Appelhans participates in the state's QuarterQuad program, which divides the county into 9,000-acre sections. Each year he goes out and logs infestations in each section of the weeds slated for updates that year; this year's list includes salt cedar, dalmation toad flax, yellow toad flax, hoary cress, perennial pepperweed, leafy spurge, diffuse knapweed and Russian knapweed. Some of the weeds on the list are of concern because of the 2013 flood; they weren't established in Logan County before but seeds could have travelled downstream in the floodwaters and taken root here, he noted.

The data from each participating county is used to estimate the impact noxious weeds has on natural and agricultural resources.

Appelhans also is required to take continuing education classes to maintain his pesticide applicator license and the various specialty licenses he holds. That includes licensing for vertabrate pests, such as prairie dogs. While he said the district doesn't use controls for prairie dogs, he can help landowners identify and connect with partner organizations that can help with those pests.

The district does have a grasshopper control plan that they implement when the forecast calls for a bad year, he said.

And while spraying pesticides is one method the district uses to control pests, it isn't the only one.

Appelhans said one of the big focuses of his job is stewardship of natural resources. "We're huge environmentalists," he said.

When faced with an infestation, Appelhans said there are a lot of steps he takes to prevent having to spray.

All pests have an "action threshold," that Appelhans uses to determine when to implement control measures. The financial cost of treatment compared to potential for economic damage from the pest is a main factor; the reason some weeds aren't up for eradication is because they are so well-established that it wouldn't be economically feasible to eliminate them, not to mention the amount of pesticide to kill them would essentially "poison the whole earth," Appelhans said.

If action is necessary, one of the options is using biological controls. Appelhans subscribes to the Palisade Insectary, which provides beneficial insects that he can use in appropriate situations. There are some locations where using chemical sprays is too hazardous, Appelhans said, either because of a sensitive environment such as along waterways or because of proximity to homes or livestock. He cited an example from his previous job with the city of Sterling, where they used a parasitic nematode to address a grub problem in a city park. It took care of the problem without requiring chemicals that could have been toxic to park users, and while it was more expensive up front than a chemical control would have been, Appelhans said the treatment lasted for two years, saving money in the long run.

He also noted that he has located a stand of salt cedar along the South Platte River that appears to have a natural biological control of some kind - likely either a disease or insect that is killing the plant. Salt cedar, a tree that consumes large quantities of water and raises the salt content in surface soil, killing off other plant life, is a plant Appelhans would normally eradicate, but he's leaving this alone for now. If the biological control can be identified and isolated, it could be applied in other locations to eliminate the List B plant.

Another consideration is what chemical to spray. Appelhans said he rotates herbicides every two to three years, to prevent plants from adapting to the same chemical and developing a resistance to it. He noted that most of the tumbleweed seen in the area is what he terms "Roundup Ready" kochia, which has over time developed a natural resistance to the pesticide used by farmers on their crops.

Safety is an important factor in pest management. Appelhans said he tells his spraying crew members not to do any pesticide application that their not comfortable with, even if they're licensed for it. He also said anyone applying any pesticide, including common non-restricted chemicals for residential users, needs to follow the label instructions and use the protective equipment. Just because a pesticide's use is not restricted to licensed applicators, doesn't mean it's safe, Appelhans noted. "If it's made to kill plants and animals, it's probably not good for you," he said, adding that it's important to follow the directions to "protect yourself and others."

While the district doesn't do pest management within cities or towns, Appelhans can provide information and advice for all property owners on how to take care of weed problems. His office is located in the Human Services Building at 508 S. 10th Avenue, Sterling (inside the Extension Office), and he can be reached at 970-522-3200 or dappelhans@loganco.gov.

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